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本研究分別比較實驗室製備污染高嶺土與現地污染場址對不同重金屬之去除效果。在實驗室製備污染高嶺土之實驗結果顯示： TTA(2-Thenoyltrifluoroacetone)對重金屬鉛沒有錯合能力。此外，當操作條件為Tc:60℃、Pc:290 atm、TTA濃度0.01M、反應時間30分鐘，實驗顯示重金屬銅、鋅、鎳去除率都可達70%以上。而污染場址之污染土壤的萃取實驗結果則顯示：銅、鋅、鎳的去除效率分別為58.1%、41.4%、31.3%。
Supercritical fluid extraction is one of the new methods of treatment of soil pollutions. In this study carbon dioxide supercritical fluid with chelating agents is used to extract heavy metals from contaminated soils.
The chelating agents used in this research are EDTA-2Na and 2 - thenoyl trifluoroacetone(TTA). It was found that EDTA-2Na aqueous phase chemical substance is so difficult to dissolve in carbon dioxide supercritical fluid that lead extraction ineffective. In addition, TTA can dissolve in carbon dioxide supercritical fluid, and the effect of extraction of heavy metals from contaminated soils is more significant.
In this research, the results of removal of four heavy metals from polluted kaolin prepared in the laboratory were compared to the contaminated site soil. The results show that the lead ions cannot complex with TTA. When the experimental conditions about Tc is 60 C, Pc is 290 atm, the concentration of TTA is 0.01M, reaction time is 30 minutes, the results of removal rate of heavy metals copper, zinc, nickel from polluted kaolin prepared in the laboratory were up to 70% or more. The same treatment apply to contaminated site soil, heavy metals removal efficiency are declined. The removal efficiency of copper, zinc, nickel from contaminated site soil were 58.1%, 41.4%, 31.3%, respectively.
Comparing the impact of different heavy metal ions competing with each other, the removal efficiency showed that Cu > Zn > Ni. For the outlook of extractable metals ion amount, the extract method of carbon dioxide supercritical fluid with chelating agents is more suitable for multi-polluted soils.
Keywords: heavy metals, supercritical fluid, chelating agents, soil pollution